One thing I have noticed is that I have noticed is that these traits show up on Mage/Wizard templates a lot. My best guess for this is a reference to Catherine Kerr's Devery Cycle, but we never get any rules for such a system (Fantasy touches on it, but never gives any rules)

In magic systems without default rolls it lets you learn spells that you have read once, but don't have a teacher or reference for with you (like from scrolls that you already used in the spell magic system).

In systems that have defaults the +5 or +10 to learn a skill from default helps a lot.

In systems with a ton of esoterica being able to recall ritual components, true names, or arcane phrases from some once-read grimoire is pretty useful.

So really it seems to be generally useful for wizard-types, regardless.

Well, in real life I had an argument with my (at the time) friend that ended up with him contradicting several of his earlier statements dating from months before. Some further questioning lead to me completely unraveling his facade of caring for me except as a competent hireling and ego boost. Needless to say, he's no longer my friend.

And that's just one of many examples in my life about how you have a huge advantage over liars if you have a better memory than them. And I remembered the first Russian scenario from Empire Earth a few weeks ago where you had to lead Grigor to a potato truck to then head to Volgograd, and had tried to find from which game it was ever since. The game came out in 2001, I tried it at someone's home around that time, and I was 8 at that time. I clearly remembered allying with the garrisons by sending diplomats and tribute, and failing to pierce the laser tower defenses. So I'd be tempted to allow a Detect Lies roll at no penalty against a recurring liar, or maybe with a bonus for photographic memory.

Though I will have to add that I consider Detect Lies to be a cinematic skill at best, and supernatural one at worst and do tend to charge Unusual Backgrounds if someone wants to take it.

I have something like Eidetic Memory (1st level) in Real Life and find it endlessly useful. For example, it's the base of my otherwise shaky Mathematics Skill. It cuts way down on doing math problems twice. It also adds a lot to the default to Land Navigation.

In one 3e game where I was going into a situation with mostly strangers I gave the character Eidetic Memory 1 (30pts).

I knew that I was going to be the oldest in the group and (except for the GM) the one with the most Hidden Lore (Gurps) and such like. So I wanted the character's position relative to the other characters to mirror my relative advantages to the other players. It worked very well.

This character was a 500 year old Archmage with 500pts in spells and 100pts in mundane Skills so he did make a profit but it was an unlimited pts game so it was still mostly there for characterization. I certainly didn't need to munchkin pts and that didn't work on characters with any significant limitations to their cp budget anyway.

EM also went onto the sheet of my first 4e character. This time it was mostly because he was genetically engineered and it's a very strong candidate for anyone with a good budget for augmentations.

I'd add it to many hypothetical characters I might make in 4e in the future. I'm notorious for my memory in my gaming circle and it's just easier if my characters would actually remember the same things I do.

I saw Photographic Memory put to good use by a DF Wizard. Mostly as a replacement for careful mapping and note-taking. "Which way was it to the exit? What was that sage's name?" And also for spell acquisition, though that's only needed in the kind of game where the GM requires rolls to learn things super-quickly.

In my current GURPS Fantasy campaign, one of the seven humanoid races, the trolls, have the racial traits of Dyslexia and Eidetic Memory.

My GM gave dwarves Absolute Direction and Eidetic Memory. They dislike riding animals and even more strongly dislike things like ships or teleporters because upon death, their ghosts must retrace all their living steps on the way to the afterlife.

As I GM mostly pbp these days, EM/PM is mostly unused as the players could just go back through the thread(s) to find the answer. None of PCs I have in my games have the trait. If someone did, perhaps there'd be some creative uses that go beyond that.

Well, in real life I had an argument with my (at the time) friend that ended up with him contradicting several of his earlier statements dating from months before. Some further questioning lead to me completely unraveling his facade of caring for me except as a competent hireling and ego boost. Needless to say, he's no longer my friend.

And that's just one of many examples in my life about how you have a huge advantage over liars if you have a better memory than them. And I remembered the first Russian scenario from Empire Earth a few weeks ago where you had to lead Grigor to a potato truck to then head to Volgograd, and had tried to find from which game it was ever since. The game came out in 2001, I tried it at someone's home around that time, and I was 8 at that time. I clearly remembered allying with the garrisons by sending diplomats and tribute, and failing to pierce the laser tower defenses. So I'd be tempted to allow a Detect Lies roll at no penalty against a recurring liar, or maybe with a bonus for photographic memory.

Though I will have to add that I consider Detect Lies to be a cinematic skill at best, and supernatural one at worst and do tend to charge Unusual Backgrounds if someone wants to take it.

Tangent -- perhaps detect lies may be less than cinematic and broken if you give a base amount of time and "talk" for it to be used. You have to really engage with the target, and they have to give enough details for you to spot inconsistencies. And then I suppose you can use time bonuses from there. Might be nice to have a realistic version. Thanks.